Visio VX32L-HDTV10A - no picture

[ahickman]

Along with several other flatscreens I received from the dump last week, I procured a nice VX32L-HDTV10A which had no picture at power up. A couple of quick searches on this site and Google indicated that the U33 voltage regulator on the main board was suspect. Ordered a replacement from Digikey (P/N 497-1229-1-ND) and replaced it. Viola! Set works nicely.

Removing the chip was very difficult as it had epoxy betwen it and the circuit board. Had to carefully clip the legs and desolder them separately. Then had to gingerly tap a razor blade under the chip to dislodge it. Also found that a chisel tip was far superior to desoldering than a pointed tip.

Thanks to this forum, I have yet another LCD to be used as a bargaining tool or gift!

[tom66]

Re: Visio VX32L-HDTV10A - no picture

Glad to hear you fixed it. However, there is a far easier way to remove a regulator:

- Glob solder over the three bottom pins with the soldering iron. Cover them up well.
- Heat up the glob for 15-30 seconds with the iron.
- Using the soldering iron apply light pressure in one direction to the regulator. It will quickly move.
- Use solder wick to clean up the pads.

[ahickman]

Re: Visio VX32L-HDTV10A - no picture

I have heard of this method, but get so intimidated when there are so many teeny, tiny little SMD pieces so close to the pads. Not that a razor blade with pressure applied to it is any safer

[tom66]

Re: Visio VX32L-HDTV10A - no picture

It is worrying. However, remember that surface mount parts rely on surface tension to hold them on during wave solder processes. It's much the same thing. They are designed to resist it without moving. If you directly push or heat them though, you could move them.

[retiredcaps]

Re: Visio VX32L-HDTV10A - no picture

A couple of quick searches on this site and Google indicated that the U33 voltage regulator on the main board was suspect.

I wonder if Vizio got a bad batch or they under engineered the part? Or maybe that should have used a bigger physical package and the regulator is dying due to heat?

[tom66]

Re: Visio VX32L-HDTV10A - no picture

I've pulled a few 1117's. I suspect it is due to the low cost of these devices (poor quality) and cost-based engineering, running them near maximums.

[budm]

Re: Visio VX32L-HDTV10A - no picture

If the 1117 series made by US based companies are better than the Chinese no name companies. There are so many Chinese semiconductor companies that I never heard off.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

I have an unrelated question on this same model Visio. Can a main board from a VX37LHDTV10A numbered Vizio 0171-2272-2174 3637-0052-0395 be used in a Visio 32" set? The 32" board is a 0171-2272-2174 3632-0202-0150 .The 32" set had a bad U33 but now that I have good voltage it still will not turn on. The Visio logo on the front does turn white. I have a good 37" board and just want to know if that can be used. Thanks--

[tom66]

Re: Visio VX32L-HDTV10A - no picture

If the panel is the same manufacturer i.e. both are LG display, both are Samsung... then yes.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

Tom--
thanks for the answer. On the 32" set I have checked all the DC-DC converters and the outputs are to spec yet the set will still not turn on. the Visio logo turns white and I am able to turn it on and off with the side button. On Ebay someone is selling a kit of 4 parts that are supposed to "cure" this problem. What 4 parts (other than the DC -DC converter chips) do you think they are? I have checked most of the caps and they seem fine.

[budm]

Re: Visio VX32L-HDTV10A - no picture

How is the voltage on U7? Its input if from U33's output.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

All of the 1117's now have voltages that are within spec including U7. What is puzzling to me is that I am not having the usual trouble I read about in the forum. My set will turn off and on. It does have the usual problem where there is no sound and the back lights do light up. The Visio logo does turn White.

I appreciate you taking the time to help me out.
Alan
AA6DW

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

I should have been more clear in answering your question. U33 was bad causing two other 1117's to malfunction. U7 being one of them. I replaced U33 and all the voltages went to spec. The output of U7 is now 1.25V. No change in operation after the replacement of U33.

[johnboy1313]

Re: Visio VX32L-HDTV10A - no picture

Have you checked if the backlights work on this set? Have you connected a source and checked for sound? When you say no picture, is it a dark screen or a blue "no signal" screen.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

I have not checked for sound. The back lights do go on and off as they should when I push the side on-off button.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

It has a dark screen not blue.

[budm]

Re: Visio VX32L-HDTV10A - no picture

"I should have been more clear in answering your question. U33 was bad causing two other 1117's to malfunction. U7 being one of them. I replaced U33 and all the voltages went to spec. The output of U7 is now 1.25V. No change in operation after the replacement of U33." Thanks for the clarification, that is usually happen, I usually ending up repalcing the the U7 also.
Can we see the pictures of all the boards? We need to chek the BL_ON (Inv_on) signal next.

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

I will post some photos tonight. The back lights are turning on and off. If the BL_ON (Inv_on) signal was bad would they still turn on?

[johnboy1313]

Re: Visio VX32L-HDTV10A - no picture

Have you checked the fuse on the T-Con board?

[Acorlin]

Re: Visio VX32L-HDTV10A - no picture

I have not checked T-Con board at all. Will check tonight.